“We’re profoundly grateful to the fans who not only watched Line Of Duty but also made it such a talking point, and to BBC Two for this rare and immensely flattering opportunity," said Mercurio.

"For series three and four, I can promise two explosive new cases for AC-12, new guest stars as police officers investigated for corruption, further twists and turns from the loose ends of series two, and maybe even some surprise reappearances...”

Viewers will be hoping one of those will be from Hawes whose character was last seen serving a life sentence for her role in the crime. However, details of dodgy "Dot" Cottan's involvement were revealed to viewers during the series finale and his indictment could, theoretically, result in her release from prison.

Controller of BBC drama, Ben Stephenson, described the two-series order "the easiest decision I have made," while executive producer, Simon Heath, added, "it's a great chance to go deeper into the murky world of AC-12."

The news coincides with the 50th anniversary of BBC2 and is one of several new commissions announced by acting controller, Adam Barker.

Paul Whitehouse will bring his Radio 4 comedy Nurse to the channel for a four-part TV series following Esther Coles’ Community Psychiatric Nurse into the homes of her patients, many of whom are played by Whitehouse himself.

A raft of documentary series have also been unveiled. Amanda Foreman will present The World Made By Women, a new four-part series exploring 20,000 years of women's history while an accompanying collection of documentaries looking at suffragettes, Joan of Arc and the women of Ancient Egypt will be fronted by Amanda Vickery, Helen Castor and Joann Fletcher.

Beyond Human will see physicist Helen Czerski and biologist Patrick Aryee look into the world of animal senses, while four-part series Foster Parents will uncover different types of foster care and the services that support them, and War in Afghanistan will mark the withdrawal of British troops and examine the legacy of the Afghan conflict.